Chapter 3

Question 1

What is the lowest tier of operator in terms of precedence.

Answer 1

Assignment operators

=, +=, -=, *=, /=, %=, &=, ^=, |=, «=,&raquo_space;-,&raquo_space;>-

Question 2

What are the 3 highest tier of operators in terms of precedence.

Answer 2

Post-unary operators, var++, var–
Pre-unary operators, ++var, –var
Other unary operators, -, !, ~, + (type)

Question 3

how many variables or operands does a unery operator require.

Answer 3

one.

Question 4

List all the operator types in order (12 in total)

Answer 4

Post-unary operators, var++, var--
Pre-unary operators, ++var, --var
Other unary operators, -, !, ~, + (type)
Multiplication/division/modulus, *, /, %
Addition/subtraction, +, -
Shift operators <>, >>>
Relation operators , <=, >=, instanceof
Equal to/not equel to ==, !=  
Logical operators &, ^, | 
Short-circuit logical operators &&, ||
Ternary operators, boolean expression
Assignment operators 
=, +=, -=, *=, /=, %=, &=, ^=, |=, <<=, >>-, >>>-

Question 5

what does the following unery operator do : !

Answer 5

Flips a boolean value. !False() = true() and vice versa.

Question 6

what does the following unery operator do : -

Answer 6

it forces a numeric value into the negative.

Question 7

what is the value of : A if B is 3.

int A = ++B * 5 / B–;

Answer 7

a = 5
First the post-unery operator is triggered.
setting B To 2.
Then the pre-unery operator is triggered
Setting B to 3
the equation is then evaluated left to right
3 * 5 / 3 =

Question 8

list all the unary operators

Answer 8

! flips a boolean
\+ force a number to a positive value
- force a number to a negative value
\++ increments a value by 1
-- decrements a value by 1
(type)  casts a value to a specific type

Question 9

list all the binary operators

Answer 9

\+ Adds two values
- subtracts two numeric values
* multiplies two numeric values
/ devides one numeric value by another
% modules returns the remainder after division of one numeric value by another.

Question 10

what happens when two values have different numeric data types

Answer 10

Java will promote the lower value to the higher value.
So 
int + long = long 
or 
byte + int = int

Question 11

what happens when a integral value is part of a operation with a floating value.

Answer 11

the integral value is treated as the floating value.
int + double = double
int + float = float

Question 12

what happens to a byte, a short or a char when it is part of a binary operations.

Answer 12

They are promoted to ints.
byte + byte = int
byte + char = int
short + char = int

Question 13

what does this assignment operator do : =

Answer 13

it assigns a value to a variable.
so
var = (complex method)
var = (result of complex method)

Question 14

what happens when we use casting on values in java.

Answer 14

It forces the output of a numeric operation into a certain value. 
var A = short + short 
A = int because of numeric promotion rules.
but 
var B = (short) (short + short) 
B = short because of casting. 
short C = short + short 
//Does not compile 
Because the compiler knows that the numeric promotion rules forces the outcome into a int. Casting is required here to allow the operation to compile.

Question 15

when is it required to use casting in java

Answer 15

When ever the code goes from a larger numerical data type to a smaller numerical data type.

Question 16

what happens when a numeric value suffers from overflow or underflow.

Answer 16

When the outcome of a numeric operation does not fit a datatype, java will 'wrap around' to the lowest negative value and continue counting from there. 
byte maxByte = 128
byte overflowByte = maxByte + 1
byte IsaneByte = maxbyte + maxbyte
overflowByte = -127
insaneByte = 1

Question 17

What are the four compound assigment operators and what do they do.

Answer 17

These operators set the value of the left operand by adding, subtracting, multiplying or dividing by the right operand.

+= adds
-+ subtracts
*= multiply
/= divides

Question 18

in what way is a compound assigment operator more then just a short hand to write code.

Answer 18

These operators also 'take care' of casting the value to the right type based on the left operand. 
Example
int A = int A * long B 
//does not compile because the outcome is a long and long does not match a int
Int A *= long B
//Does compile, because the operator casts the result into a Int. If the outcome is to big for a int the java "overflow" result will be the value of A.

Question 19

what are the equality operators in java and what do they do.

Answer 19

== and !=
== returns true if the left and right operand match. 
!= returns true if the left and right operand DO NOT match. 

Numeric datatypes are promoted for the this operation.
boolean check = int 5 == double 5.00
check = true()

Question 20

what is the value of “B”
boolean A = false
boolean B = (A = true)

Answer 20

the value of B = true
This is because of the assignment operator used in the operation that sets the value for B.
Boolean B would have been false if :
boolean B = (A == true)

Question 21

what is the value of A and B

File 1 = new File("new file.txt");
File 2 = new File("new file.txt");
File 3 = 2;
Boolean A = (1 == 2);
Boolean B = (2 == 3);

Answer 21

A = false
1 and 2 point to two different objects (File 1 and File 2). based on the same class.
B = true
2 and 3 point to the same refrence of a object. Both point to File 2.

Question 22

what are the 5 relational operators and what do they do.

Answer 22

All relational operators return a boolean value based on the relation between de left and right operand.

< true if left is smaller than right
<= true if left is smaller than or equel to right.
> true if left is bigger than right
>= true if left is bigger or quel to right.

A instanceof B = true
if A is a reference to a class, sublass or interface that is named in B

Question 23

how many objects are created in this code snippet.

Integer count = Integer.valueOf(9)
Number num = count
Object ob = count

Answer 23

one object (count) is created.

Question 24

what are the three logical operators and how do they work.

Answer 24

& = logical AND
returns true if both operands are true.
| = Inclusive OR
returns true if at least one operand is true.
^ = exclusive XOR
returns true if one operand is true and one is false.

Question 25

what are the short circuit operators and what do they do.

Answer 25

&& = Short Circuit AND
returns true if both operands are true, in addition if the left operand is false it will not evaluate the right operand.

|| = Short-crcuit OR
returns true if at least one operand is true. If the left operand is true the right operand will not be evaluated.

Question 26

what is the value of “count” after this snippit has been run.

int count = 6;
boolean test = (count >= 6) || (++count <= 7)

Answer 26

value = 6
The increment operator on the right side of the expression is never evaluated because of the short circuit OR operator.
If the short circuit AND was used it would have been 7

Question 27

how many operands does a ternary operator require and what is the correct syntax.

Answer 27

3 operands.
1 the value to set on the left.
2 the “if” operand, This operand is the value for the first operand if a expression is met between 1 and 2..
3 the else operand, this operand is the value of the first operand if the expression between 1 and 2 is not met.

Syntax
First = (expression) ? SecondOperand : ThirdOperand

Question 28

there are currently 12 different operator types. These can furthermore be devided over 3 groups. Name these groups.

Answer 28

Unery (one operand)
Binary (two operands)
Ternary (three operands)